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February 3, 2023



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M3 comes home


Known by its initials as M3 (M is for Mirror), the Gran Telescopio Canarias' (GTC's) tertiary mirror has arrived at the Observatorio del Roque de los Muchachos (ORM).

Now that the mirror is here, we need to make sure that everything is present and correct. This includes testing the M3 Handling Tools - it may sound simple, but it won't be all plain sailing.

The tertiary mirror, which is made from ZerodurTM like the segments of the primary mirror, is currently being 'transported' through the insides of the GTC enclosure.

As the mirror will have to move, positioning itself inside the turret automatically to reflect light on to the folded Cassegrain and Nasmyth foci (it will be 'parked' when not in use), it will be equipped with a private 'lift'. For manoeuvring, adjusting and testing the mirror within the enclosure, however, a series of tools have had to be developed.

The first (in black) will be used to grasp the tertiary mirror. This is the M2 Handling Tool.

The second, the M3 Rocking Tool, will be used to lift the mirror into the mount at an incline of 45º - the angle at which it will be installed in the turret. This is also the tool that will be used to lift the mirror into and out of the mount for maintenance.

Finally, a third tool (in yellow), called the M3 Unit Handling Tool, will lift the mirror and its mount into the turret so that it can be fixed into the parking mechanism. This is effectively the mirror's transport system.

Natalia R. Zelman

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